Multi-speed power transmissions are used in many trucks which operate under various conditions of load, and in passenger vehicles. The trucks may be fully loaded and therefore require many speed steps or ratios in the transmission to make full use of the engine range and acceleration capabilities. The truck may also be lightly loaded or empty. Under these conditions, the operator may desire a transmission with fewer speed steps or gear ratios so that the top running gear can be reached with fewer shifts or ratio interchanges.
The passenger vehicles are generally four speed planetary transmissions, wherein the top gear is an overdrive ratio. In these transmissions, there is generally a relatively large step between the third (direct) to fourth (overdrive) ratios. This is present to take advantage of the overdrive ratio at highway speeds and greatly reduce the fuel consumption of the vehicle. However, the large step between these ratios can result in a shift feel which the driver can perceive under heavy loads. Some drivers may find this undesirable in their vehicle operation. While this occurrence does not affect the overall performance of the vehicle, it would be, from a pleaseability standpoint, better if the large step were not present.